In processing of video with sound, the original audio and original video will go through different encoders for encoding at an encoding side. A multiplexer combines the audio stream with the video stream into one stream which is then transmitted. After receiving the stream, a decoding side apparatus uses a demuxer to separate the audio stream and the video stream, and decode the audio stream and the video stream separately. Then the decoded audio content and video content are presented at a playing apparatus.
In order to avoid an audio out of synchronization with a video, conventional mechanisms generally add a timestamp in the audio and video bit streams to enable the playing apparatus to play the audio content and video content in specified order and speed.
The timestamps in the audio stream and the video stream are not dependent on each other, so the use of timestamps can not guarantee the synchronization between the audio and the video during playback.